O.K. Mistman,
Heres some steps. Turn on your Xbox and immediately hold the white button. This boots to configlive. I counted 10 seconds for the Flubber animation/Sound effect to stop and then a further 14 seconds for X3CL to appera on screen. Hold the white button further 10-15 seconds just to make sure you in X3CL.
(Hint: if you are in X3CL you should be able to FTP into your xbox and see the admin folder aboce the C drive. Make sure this is the case)
Now that you are in you have the following options:
X3ConfigLive
Bios Tools
DiskTools
EEProm Tools
Settings
Hardware Info
Reboot to dash
Cold Reboot
Power Off
Your curser always starts on the top option so DOWN 4 Times then A should select your Settings menu.
Since you are unsure of the option that your brother changed, you may need to experiment.
The settings menu has the following:
Newtork Setup
Video Regions
Video Modes
LCD Settings
Fan Speed
Set Date/time
Password Protection.
It will obviously be in either Video Regions (DOWN once then A)
or it will be in VIDEO Modes (DOWN 2 times then A)
Video Regions has the following:
PAL 1: Enabled/Disabled
NTSC U :Enabled/Disabled
NTSC J : Enabled/Disabled
VIDEO MODES has the following:
480P : Enabled/Disabled
720P : Enabled/Disabled
1080I : Enabled/Disabled
Pal 60 : Enabled/Disabled
WideScreen : Enabled/Disabled
Letter Box : Enabled/Disabled
Well that's all your menu options. Your brother may have changed any or all of these. To troubleshoot, I would start with the top of the list and work my way down choosing relevent options. Note: First time round, if your video mode is not fixed, it may be worth your while to repeat the step EXACTLY to reverse what you just did. The thinking is that if that didn't fix your problem, change it back to the way it was.
I Really do appologise for this mammoth size post. I hope you find some useful info, and if i have left anything out... let me know.
Cheers bud and good luck.